Pump



S. L. DAVIS Nov. 26, 1929.

PUMP

Filed Aug. 12, 192'7 :Jn/vento@ 'T213 S/'c/ngg Edv/'s 's0' 1M @hm "www www 32 3 l;-

UNETE PATENT OFFICE Sl'IDNlEY L. DAVIS, OF KEENE, NEW EAMPSHERE, ASSIGNOR TO MORGANMADE, INCOR- PORATED, OF KEENE, NEVI- HAIVIPSHIRE, A CORPORATION 0F vNEW HAMPSHIRE PUMP Application filed August 12, 1927. Serial No. 212,587.

My invention relates to pumps and more particularly to a pneumatic pump of the type commonly used for inflating vehicle tires.

The ordinary tire pump lcomprises a cylinder within which moves a hand operated plunger. The construction of the cylinder and particularly the manner of making the bottom air tight involves various difficulties and the present invention relates primarily to an improvement in this feature of the pump. One form of pump which is commonly used has a metal foot rest and base provided with a screw threaded hole into which the end of the pump casing is threaded. The necessity of machining and screw threading the base and cylinder makes this type of pump expensive. Another ferm is one in which the lower end of the cylinder is held against a washer in a socket in the metal base by means of screw threaded rods. Such a pump involves too many expensive parts and these are not fastened together rigidly and permanently. If, on the other hand. the metal base and the cylinder are welded together, an expensive manufacturing operation is involved. It has also been proposed to drive a solid metal plug into the lower end of the cylinder, but this does not necessarily form an air tight joint, since there will not be a driving fit between the casing tube and a solid base portion unless the interfitting parts be first accurately machined to provide substantially smooth surfaces of the proper sizes. A

Furthermore, if the plunger does not come close to the bottom of the casing, a residual volume of air is left at the lower endof the casing when the plunger has reached its maX- imum depth of stroke. This last bit of air left in the casing is under high pressure and since it does not get beyond the valve into the passage which communicates with the vehicle tire, then the pump is thereby ren# dered inefficient.

The main objects of my invention are accordingly to overcome the difficulties inherent in these prior constructions and to provide an efficient pump which may be easily and cheaply manufactured and which may be assembled without diiiiculty to form a structure which is air tight in the base, and further to provide a construction in which the parts are so shaped and arranged as to render the device capable of forcing practically all of the air from the pump casing at each stroke of the piston.

With these and other objects in view as will be apparent to one skilled in the art, my invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawings which illustrate one embodiment of my invention and in which like reference numerals indicate like parts:

Figure 1 is a vertical elevation of a hand pump, with parts broken away to show the interior construction;

Fig. 2 is a fragmentary vertical section of the lower end of the pump; and

Fig. 3 is a section on the line 33 of Fig. 1 showing the manner offastening the foot rest to the pump.

While the invention is generally applicable to other types of pumps not herein illustrated, I have shown in the drawings a hand pump comprising a tubular barrel or cylinder l0 of metal within which slides the plunger or piston 11 for forcing air from the space below the plunger through the tube 12 to an automobile tire or the like. The piston may be of any suitable construction and in the present case it is mounted on a slidable rod 14 at the upper end of which is fixed a handle 15. A wooden plug 16 is fastened into the upper end of the barrel 10 by means of screws 17 or the like and the rod 14 slides through a centrally located aperture therein. A spring 18 loosely mounted on the rod 14 above the piston serves to absorb shocks upon the up-v ward movement of the piston by striking the underside of the cap 16 and cushioning the blow. The lower end of the piston may comprise a metal plat-e 20 which supports a cupshaped leather washer 21 of the usual variety7 and above which is a further metal plate 22, the parts being so arranged that the leather washer is held between the two metal plates. The upper plate is held in position by means of lugs 23 stamped out of the side of the rod 14 and the lower end of the rod 24 is headed over to rivet the parts securely and rigidly in place. The construction so far described is all common in the art and does not pertain to the present invention.

rlfhe barrel or casingV l0 is made of drawn metal or of a strip welded together along one side and is flexible and deformable to a certain extent. ln order that the lower end of this barrel may be closed by an air tight cover, l provide a cap 25 which has a substantially cylindrical wall of deformable inaterial, and this cap is so shaped and constructed that it may be forced into the lower end of the barrel to form a tight driving lit. The cap 25 is preferably made of drawn metal and it has a long extensive outer cylindrical surfacewhich serves to lit tightly against the inner surface of the barrel. Owing to the fact that the cap is forced into the barrel under high pressure, if the two parts do not correspond eXactly in shape and size, they nevertheless will make a tight fit since they are both deformable and can conform to each other-s surface irregularities A simple way of fastening a foot rest to the pump comprises making apertures 30 through the walls of the cap and barrel and then springing into place the resilient arms 3l of a U-shaped wire member 32. These holes are'preferably pierced `after the cap has been assembled into position so that the act of making the hole tends Ito merge the metal of the cup and the'tube together and thus aids further in holding the parts assembled. lt will be, however,'apparent that one may provide holes in 'the parts beforehand and assemble them in aligned positions.

A flexible tube l2 is fastened onthe end of a nipple 35 which is provided with a hole therethrough and this is in turn screwed into the threaded end of a plug' likewise apertur'ed 'for the passage of air therethrough. This plug 36 is suitably fastened into the side of the casing 10 and, as illustrated in Fig. 2, lthis may be done by reducing the inner end of the plug to form a shoulder and then Vatter inserting the plug into `an opening of proper size in the casing wall 'the inner end of the plug is headed lover to secure the parts together. In order to prevent 'the fair under i pressure from esca-ping into the' cylinder when the piston rod is moved upwardly, a. suitable valve Yis provided. This may comprise a ball 38 located in an 'enlarged portion of the aperture of the plug, as .illustrated in Fig. 2. This ball is arranged to `be seated against a properly shaped conical surface 39 at the lower end of the enlarged aperture. The lower vend ofthe nipple 35 may be provided with ribs 40 er the like which prevent the ball from `closing the passage through the nipple. lt will be understood that this particular construction is common and that any suitable type of valve may be provided.

Upon inspection of Fig. 2, it will be apparent that the inner surface of the cap 25 is substantially flat and it is so positioned that the plunger may come down to it and thus remove practically all of the air from the casing. ln order to provide space for the air to escape into the tube and yyet permit the plunger to move downwardlyto the desired extent, l for-m the cap as illustrated witha sloping surface 42 which provides a small passage from the main cylindrical portion of the entrance of the opening through the plug 36.

lt will now be apparent that I have provided a novel base construction for an air pump that is efficient, economical and tighter than 'those in common usage. rlhe closure cap fitting into the 'lower end of the barrel is of the proper gage to conform to the inner surface of the barrel and the two are assembled with a driving fit, thus forming an air tight rlfhe depression formed by the sloping wall l2 in the top `of the cup forms an air outlet well which allows the piston to come flush with the top of the cup and thus expel substantially all of the air in the casing. This obviously increases the efficiency of the pump. "his construct-ion is such that the parts may be put together easily without the need of threading or welding the par-ts, and

it is merely necessary to rivet the plug 36v to the side of the casing and then force the cap 25 into place.

Having thus described my invention, what l claim as new and desire to sec-ure by Letters Patent is:

l. ln va pump, the combination of a barrel which is made Aof deformable material, 'a piston slidably mounted therein, means for Aconducting air from the barrel, and a closure for the lower end of the barrel which comprises a cup shaped member having an imperforate top and a substantially cylindrical wall 'of deformable material which is forced with a driving fit into lirm engagement with -a wall of the barrel and thereby forms `an :air tight seal.

2. In ka pump, the combination of :a barrel which is made of deformable material, a piston slidably mounted therein, means for con-A ducting fair from the barrel, `and a closure 'cap having a cylindrical wall ofdeformable material forced with a( driving lit against the inner surface of one end of the barrel to form an air tight seal therefor and a flat top which is so arranged that the piston may force 'out substantially all Iof the air above the cap. y

8. In an air pump, the combination of a cylindrical casing, 'one end yof which is rmade of deformable material, a piston slidably mounted therein, a closure cap having a top and a cylindrical wall of deformable `material which has been forced with `a driving fit into the deformable `end of the casing, said cap being so constructed that the piston may come into substantial Contact therewith and force substantially all of the air from the barrel, and means forming a pipe connection to the interior of the casing for directing the air therefrom.

4. In a pneumatic pump, the combination of a cylindrical casingvhaving a deformable end, a piston slidably mounted in said casing, a cap having a deformable cylindrical portion forced with a driving lit into the deformable end of the casing to form an air tight seal, said cap having a top surface which is substantially flat and is adapted to permit the piston to come into Contact therewith and remove the air from the casing, one side of the cap being so shaped as to form an air passage below its inner top surface, and means including a pipe connecting with said passage for directing air from the casing.

5. In a pneumatic pump, the combination of a cylindrical barrel made of deformable material, a piston slidably mounted therein, a cap having a top plane surface and a cylindrical portion of deformable material which has been forced with a driving lit into the lower end of the barrel to form an air tight seal, said cap being so constructed as to form a small air passage beneath its top surface, an air conducting plug fastened into the wall of the barrel so as to communicate with said passage and a valve in said plug to prevent the return of air to the casing after it has been discharged therefrom.

6. In a pump, the combination of a cylindrical barrel of deformable material, a piston slidably mounted therein, a hollow closure cap having a cylindrical portion of deformable material driven into the end of the barrel to form an air tight seal, said barrel and cap having holes therethrough, and a foot rest having resilient arms sprung into said holes.

Signed at Keene, New Hampshire, this 9th day of August, 1927.

SIDNEY L. DAVIS. 

